Desuperheating and pressure-reducing valve for superheated steam



Nov. 30, 1965 TERUHIKO MATSUI DESUPERHEATING AND PRESSURE-REDUCING VALVE FOR SUPERHEA'IED STEAM 2 Sheets-Sheet 1 Filed March 29, 1963 DESUPERHEATING AND PRESSURE-REDUCING VALVE N 3 1965 TERUHIKO MATSUI I 3,

FOR SUPERHEATED STEAM Filed March 29, 1963 2 Sheets-Sheet 2 United States Patent 3 220,708 DESUPERHEATDIG AND PRESSURE-REDUCING VALVE FOR SUPERHEATED STEAM Teruhiko Matsui, Kawasaki-511i, Kanagawa, Japan, as-

signor to Maenaka Valve Works Co., Ltd, Tokyo,

Japan Filed Mar. 29, 1963, Ser. No. 268,976 4 Claims. (Cl. 26139) The present invention relates to a valve, and more particularly to a valve for reducing and decreasing pressure and temperature of superheated steam flowing in a pipe.

With conventional valve devices of this kind, the operations for reducing and decreasing the pressure and temperature of the superheated steam and for desuperheating the superheated steam have heretofore required separate devices.

Furthermore, when the steam flowing through the piping is utilized in atomizing cooling water discharged into the flowing steam to effect heat control, the once pressure-reduced steam now flows with decreased velocity and as a result the atomized droplets of cooling water discharged into the steam unavoidably grow coarse in size and are poorly mixed into the flowing steam with a resulting increase in moisture content and a decrease in desuperheating efficiency.

In order to eliminate'such defects, a system was adopted where the atomizing nozzle for cooling water isv fed with steam specifically for atomizing purpose. This system, however, had likewise the defect of difiicult operation, because of its complicated control system.

Now the present invention provides a valve device of such structure that, without the help of any other additional valve device, is capable of both the desuperheating and the pressure-reducing operation for a flowing stream of superheated steam and in the desuperheating operation, it causes the flowing steam to do work before it is reduced in pressure in such fashion that droplets of the cooling water discharged into the steam do not deposit on the piping walls in the atomization region.

It is, therefore, the primary object of the invention to provide a desuperheating and pressure-reducing valve for flowing superheated steam that avoids deposition of droplets of atomized cooling water on the piping walls in the desuperheating and pressure-reducing operations.

It is another object of the invention to provide a desuperheating and pressure-reducing valve for flowing superheated steam that is capable of uniformly atomizing the cooling water introduced into the flowing steam.

It is another object of the invention to provide a desuperheating and pressure-reducing valve for superheated steam that is capable of both the desuperheating and pressure-reducing operations without help of any additional valve device.

It is still another object of the invention to provide a desuperheating and pressure-reducing valve for superheated steam that is capable of uniformly mixing the atomized cooling water discharged into the flowing superheated steam to the maximum extent possible.

These and other objects of the invention will be apparent from the following description of the invention made on an illustrative form of embodiment thereof with references being made to the attached drawings.

The form of embodiment of the invention here described is only for the purpose of illustration and allows many modifications and variations in structural detail and is not intended to restrict the invention in scope.

FIGURE 1 is a longitudinal side section of a desuperheating and pressure-reducing valve for a flowing stream of superheated steam in accordance with the invention;

FIGURE 2 is a lateral plan section of the valve of FIG- URE 1; FIGURE 3 is a front view illustrating details of the atomizing section of the valve; and FIGURE 4 is a diagram of a piping system susceptible of automatic control and including the desuperheating and pressure-reducing valve of FIGURES 1-3.

Valve casing 1 having outer shell 2 is integrally and axially provided with inner shell 3 therewithin, which is adapted to receive a flowing stream of superheated steam, and has upper and lower valve seats 4 and 5 and a valve rod 7 extending through outer shell 2 :beyond the valve assembly and a double-seat valve block 6 actuated by the rod to control the flow of the steam.

Double-seat valve block 6 has its portions 8 and 9 tightly engageable with valve seats 4 and 5. Upon the valve block superheated steam enters into inner shell 3 and passes into the inner peripheral space of outer shell 2. Inner shell 3, into which the superheated steam enters directly, has at one end a bore 11 in which is mounted an inner nozzle element 12 having its projecting central portion 13 provided at end with a set of obliquely extending bores 14 for steam jets concentrically distributed with respect to the axis of the element. At the other end of bore 11 there is an outer nozzle element 15 having a central opening 16 for steam jets and, between itself and said central portion 13 of element 12, there is a set of projecting guide vanes 17 equidirectionally directed and obliquely inclined in the same manner as bores 14 for steam jets. These inner nozzle and outer nozzle elements 12 and 15 constitute atomizing nozzle head 18. A passage 19 extends into bore 11 and through the wall of inner shell 3 from outer shell 2, the passage 19 being connected to piping 20 for admitting cooling water.

Upon opening of the passage in valve 1 by doubleseat valve block 6, the superheated steam is released from the inner shell 3 into the inner peripheral space 10 of outer shell 2 and partly over the peripheral surface of inner shell 3, in the form of a sleeve of a dense flowing steam mass, partly through obliquely extending bores 14 which impart a tendency for the steam to flow with an axially spiral motion.

At this moment, the cooling water feed, sucked through feed piping 20 and passage 19 into bore 11 by the gen eration of negative pressure and given a direction identical with that of obliquely inclined guide vanes 17, is atomized from the top opening of atomizing nozzle head 18 into the superheated steam mass in motion there in a form of a sleeve which thereby is desuperheated and pressure reduced. The atomized cooling water is prevented by the dense steam flow in a form of a sleeve present on the outer periphery of the inner shell from directly touching and condensing in droplets on the inner Walls of casing 1 which, together with other communicating piping sections, is thereby protected from corrosion.

It is an advantage of the invention that the steam at the atomizing nozzle head may be held constant in pressure and the cooling water in its atomization into steam is independent of the amount of steam at the atomizing nozzle.

Furthermore, in accordance with the invention, the desuperheating and the pressure-reducing operation may be carried out by employing a single valve without an intricate control system. The invention provides such a valve that assures easy and accurate control of the desuperheating and the pressure-reducing operation, and is highly reliable as well as of simplified structure.

An example of piping system provided with a desuperheating and pressure-reducing valve in accordance with the invention is set forth below, references being made to FIGURE 4.

Desuperheating and pressure-reducing valve a in accordance with the invention and comprising component elements as described above mentioned is provided in superheated steam feed piping b; the section of piping extending from said valve a and feeding desuperheated and pressure-reduced steam is provided with sensitive elements c and d, the former controlling valve a through a mechanism e and the latter controlling water feed valve g in cooling Water piping 20 for feeding Water to valve :1, through a mechanism f respectively, the former by detecting the actual steam pressure of the desuperheated and pressure-reduced steam feed and adjusting the passage rate of this through valve a and the latter by detecting the actual temperature and adjusting valve g.

What I claim is:

1. A desuperheating and pressure-reducing valve provided to desuperheat and reduce the pressure of a flowing stream of superheated steam which comprises:

a valve casing;

an inner shell in axial alignment and located within said casing;

valve means including a double-seat valve block at the entry end of said shell;

an atomizing swirl nozzle at the exit end of said shell,

whereby the superheated steam flowing into said inner shell is caused to divide into two separate streams, a first stream being confined to the space between the valve casing and the inner shell and serving as a dense mass of moving steam sweeping the inner walls of said valve casing and a second stream passing through said atomizing nozzle; and means to discharge cooling water into said second stream whereby said cooling water is atomized and spiralled forward axially into the central portion of said valve casing, as it leaves said atomizing nozzle. 35

2. A piping system including in combination the desuperheating and pressure-reducing valve of claim 1 and a pressure sensitive element and a temperature sensitive element, said elements being located in said piping downstream from said valve, the first of said elements controlling the double-seat valve block so as to control the amount of steam permitted to flow into said first stream of steam and the second of said elements controlling the amount of cooling water admitted into said atomizing valve.

3. The desuperheating and pressure-reducing valve of claim 1 including means to seat and unseat both seats of the double-seat valve block at the same time; the atomizing nozzle having a head at the extreme exit end of the inner shell and being located in a central opening in said inner shell.

4. The desuperheating and pressure-reducing valve of claim 3 wherein the atomizing nozzle head is provided with bores extending obliquely to the axis of the superheated steam streams, and an outer set of guide vanes located on the outer surface of said head and also inclined obliquely in the same direction as said bores, so that the atomization of cooling water fed into said atomizing head takes place spirally of said axis.

References Cited by the Examiner UNITED STATES PATENTS 1,581,223 4/1926 Moore 239-404 X 2,138,064 11/1938 Howell 261-39 X 2,276,055 3/ 1942 Mastenbrook 236-12 2,276,073 3/ 1942 Tidd 261-161 X 2,293,314 8/1942. Spence 236-12 X 2,703,260 3/1955 Olson et a1 239-404 3,034,771 5/1962 Harris 122-459 X HARRY B. THORNTON, Primary Examiner.

T. R. MILES, Assistant Examiner. 

1. A DESUPERHEATING AND PRESSURE-REDUCING VALVE PROVIDED TO DESUPERHEAT AND REDUCED THE PRESSURE OF A FLOWING STREAM OF SUPERHEATED STREAM WHICH COMPRISES: A VALVE CASING; AN INNER SHELL IN AXIAL ALIGNMENT AND LOCATED WITHIN SAID CASING; VALVE MEANS INCLUDING A DOUBLE-SEAT VALVE BLOCK AT THE ENTRY END OF SAID SHELL; AN ATOMIZING SWIRL NOZZLE AT THE EXIT END OF SAID SHELL, WHEREBY THE SUPERHEATED STEAM FLOWING INTO SAID INNER SHELL IS CAUSED TO DIVIDE INTO TWO SEPARATE STREAMS, A FIRST STREAM BEING CONFINED TO THE SPACE BETWEEN THE VALVE CASING AND THE INNER SHELL AND SERVING AS A DENSE MASS OF MOVING STEAM SWEEPING THE INNER WALLS OF SAID VALVE CASHING AND A SECOND STREAM PASSING THROUGH SAID ATOMIZING NOZZLEF AND STREAM TO DISCHARGE COOLING WATER INTO SAID SECOND STREAM WHEREBY SAID COOLING WATER IS ATOMIZED AND SPIRALLED FORWARD AXIALLY INTO THE CENTRAL PORTION OF SAID VALVE CASING, AS IT LEAVES SAID ATOMIZING NOZZLE. 